A plan to privatize the nation’s air traffic control system could hurt service and add costs at small and mid-sized airports, according to a coalition opposing the proposal.

Sioux Falls Mayor Mike Huether is among hundreds of mayors who signed a letter to Congress this week warning about the potential consequences of a privatizing air traffic control.

“Privatization would hand over decisions about infrastructure funding, taxes and fees, consumer complaints, noise, and many other priorities, to a board of private interests dominated by the commercial airlines,” the letter says. “These are the same airlines that have cut back flights to smaller communities by more than 20 percent in recent years, and have stated their intent to divert investment from small and mid-sized communities to large ones where the airlines are most profitable.”

The letter was coordinated by the Alliance for Aviation Across America (AAAA), a nonprofit representing more than 6,300 airports, businesses and pilots. It’s in response to a proposal by Pennsylvania Congressman Bill Shuster to transfer management of air traffic control from the Federal Aviation Administration to a private nonprofit.

Supporters of the proposal, including most large commercial airlines and the National Air Traffic Controllers Association, argue it would make operations more efficient and help the industry to advance technologically at a faster rate.

Huether declined an interview Monday but said in an email that he defers to the position of U.S. Sen. John Thune, R-South Dakota, who serves as chairman of the Senate’s Committee on Commerce, Science and Transportation and has publicly urged colleagues to shelve privatization efforts.

“Senator Thune has direct knowledge on the topic at hand and I am in support of his work and the legislation he has put forth,” Huether wrote.

Sioux Falls Regional Airport Executive Director Dan Letellier said too few details are known about what privatization would look like to know if it would hinder or benefit the airport.

That doesn’t mean there aren’t concerns, though. The airport collects a fee on every airline ticket sold to help pay for construction projects like an upcoming resurfacing of a main runway that could cost up to $20 million. Under privatization it’s unclear if the airport could continue to collect that fee, Letellier said.

And privatization could make it more expensive to fly corporate jets and personal planes, which could be subjected to user fees for each landing, Letellier said.

“From a commercial service standpoint, I don’t think that privatizing the air traffic control organization would have any impact on the level of commercial service,” Letellier said. “It’s the impact on the private individual and their ability to have the freedom to have an aircraft and fly on their own.”

In Sioux Falls, the FFA has 33 employees working at the air traffic control tower, including 22 controllers and 11 engineers.

Read the letter signed by U.S. mayors against privatizing air traffic control: